In Java, which is the most recommended class for dictionary data structure?

Question

I need a data structure to store users that should be retrieved by id. I noticed that there are several classes that implement the map interface. What should be my default choice? All of them seem to me completely equivalent.

Answer 1

This probably depends on how many users you plan to have, and if you need to order them or just get individual items by id.

HashMap - , put get, .

TreeMap , log (n) , .

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Answer 2

concurrency: java.util.HashMap

Concurrency: java.util.concurrent.ConcurrentHashMap

, , TreeMap LinkedHashMap.

Answer 3

Java, Implementations.

Answer 4

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Answer 5

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Answer 6

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Have you considered using a database to store this information? Even if it is SQLite , it will probably be easier than storing your user database in program code or loading the entire data set into memory each time.